4606 Saheki, provisional designation , is a stony Flora
asteroid
An asteroid is a minor planet—an object larger than a meteoroid that is neither a planet nor an identified comet—that orbits within the Solar System#Inner Solar System, inner Solar System or is co-orbital with Jupiter (Trojan asteroids). As ...
from the inner regions of the
asteroid belt
The asteroid belt is a torus-shaped region in the Solar System, centered on the Sun and roughly spanning the space between the orbits of the planets Jupiter and Mars. It contains a great many solid, irregularly shaped bodies called asteroids ...
, approximately 7 kilometers in diameter.
The asteroid was discovered on 27 October 1987, by Japanese astronomer
Tsutomu Seki
is a Japanese amateur astronomer and discoverer of minor planets and comets, born in Kōchi, Japan.
Career
Tsutomu Seki is the Director of the Geisei Observatory in Kōchi, and in charge of the Comet Section of the Oriental Astronomical Ass ...
at
Geisei Observatory
The list of asteroid-discovering observatories contains a section for each observatory which has discovered one or more asteroids, along with a list of those asteroids.
For each numbered asteroid, the Minor Planet Center lists one or more discov ...
, Japan.
It was later named after Japanese astronomer
Tsuneo Saheki.
Classification and orbit
''Saheki'' is a member of the
Flora family
The Flora family (''adj. Florian''; ; also known as the Ariadne family) is a prominent family of stony asteroids located in the inner region of the asteroid belt. It is one of the largest families with more than 13,000 known members, or approx ...
, one of the largest families of
stony asteroids. It orbits the Sun in the
inner main-belt at a distance of 2.0–2.5
AU once every 3 years and 5 months (1,234 days). Its orbit has an
eccentricity
Eccentricity or eccentric may refer to:
* Eccentricity (behavior), odd behavior on the part of a person, as opposed to being "normal"
Mathematics, science and technology Mathematics
* Off-Centre (geometry), center, in geometry
* Eccentricity (g ...
of 0.10 and an
inclination
Orbital inclination measures the tilt of an object's orbit around a celestial body. It is expressed as the angle between a reference plane and the orbital plane or axis of direction of the orbiting object.
For a satellite orbiting the Eart ...
of 3
° with respect to the
ecliptic
The ecliptic or ecliptic plane is the orbital plane of Earth's orbit, Earth around the Sun. It was a central concept in a number of ancient sciences, providing the framework for key measurements in astronomy, astrology and calendar-making.
Fr ...
.
The first
precovery
In astronomy, precovery (short for pre-discovery recovery) is the process of finding the image of a celestial object in images or photographic plates predating its discovery, typically for the purpose of calculating a more accurate orbit. This ha ...
was taken at
Palomar Observatory
The Palomar Observatory is an astronomical research observatory in the Palomar Mountains of San Diego County, California, United States. It is owned and operated by the California Institute of Technology (Caltech). Research time at the observat ...
in 1953, extending the asteroid's
observation arc
In observational astronomy, the observation arc (or arc length) of a Solar System body is the time period between its earliest and latest observations, used for tracing the body's path. It is usually given in days or years. The term is mostly use ...
by 34 years prior to its discovery.
Physical characteristics
Rotation period
In January 2009, a rotational
lightcurve
In astronomy, a light curve is a graph (discrete mathematics), graph of the Radiance, light intensity of a celestial object or region as a function of time, typically with the magnitude (astronomy), magnitude of light received on the ''y''-axis ...
of ''Saheki'' was obtained from photometric observations by
David Higgins at Hunters Hill Observatory, Australia. Lightcurve analysis rendered a well-defined
rotation period
In astronomy, the rotation period or spin period of a celestial object (e.g., star, planet, moon, asteroid) has two definitions. The first one corresponds to the '' sidereal rotation period'' (or ''sidereal day''), i.e., the time that the objec ...
of hours with a brightness variation of 0.56 in
magnitude
Magnitude may refer to:
Mathematics
*Euclidean vector, a quantity defined by both its magnitude and its direction
*Magnitude (mathematics), the relative size of an object
*Norm (mathematics), a term for the size or length of a vector
*Order of ...
().
Two months later, in March 2009, a second lightcurve was obtained at the Via Capote Observatory , California. It gave a period of and an amplitude of 0.68 in magnitude ().
Spin axis
In 2013, an international study modeled a lightcurve with a concurring period of 4.97347 hours and found a
spin axis
Rotation or rotational/rotary motion is the circular movement of an object around a central line, known as an ''axis of rotation''. A plane figure can rotate in either a clockwise or counterclockwise sense around a perpendicular axis intersect ...
of (44.0°, 59.0°) and (222.0°, 68.0°) in
ecliptic coordinates
In astronomy, the ecliptic coordinate system is a celestial coordinate system commonly used for representing the apparent positions, orbits, and pole orientations of Solar System objects. Because most planets (except Mercury) and many small So ...
(λ, β), respectively ().
Diameter and albedo
According to the survey carried out by the
NEOWISE
Wide-field Infrared Survey Explorer (WISE, observatory code C51, Explorer 92 and MIDEX-6) was a NASA infrared astronomy space telescope in the Explorers Program launched in December 2009.. . WISE discovered thousands of minor planets and nu ...
mission of NASA's
Wide-field Infrared Survey Explorer
Wide-field Infrared Survey Explorer (WISE, List of observatory codes, observatory code C51, Explorer 92 and MIDEX-6) was a NASA infrared astronomy Space observatory, space telescope in the Explorers Program launched in December 2009.. . WISE L ...
, ''Saheki'' has a high
albedo
Albedo ( ; ) is the fraction of sunlight that is Diffuse reflection, diffusely reflected by a body. It is measured on a scale from 0 (corresponding to a black body that absorbs all incident radiation) to 1 (corresponding to a body that reflects ...
of 0.33 and a diameter of 6.7 kilometers,
while the ''Collaborative Asteroid Lightcurve Link'' calculates a diameter of 7.1 kilometers, based on an assumed albedo of 0.24, derived from
8 Flora
8 Flora is a large, bright main-belt asteroid. It is the innermost ''large'' asteroid: no asteroid closer to the Sun has a diameter above 25 kilometers (20% that of Flora), and not until 20-km 149 Medusa was discovered was an asteroid known to o ...
, the Flora family's namesake and largest member.
Naming
This
minor planet
According to the International Astronomical Union (IAU), a minor planet is an astronomical object in direct orbit around the Sun that is exclusively classified as neither a planet nor a comet. Before 2006, the IAU officially used the term ''minor ...
was named after Japanese astronomer and president of the ''Toa Astronomical Society'', Tsuneo Saheki (1916–1996). Over half a century, Saheki as gathered large inventory of observational data of the planet Mars.
The Martian crater ''
Saheki'' is also named in his honour. The official naming citation was published by the
Minor Planet Center
The Minor Planet Center (MPC) is the official body for observing and reporting on minor planets under the auspices of the International Astronomical Union (IAU). Founded in 1947, it operates at the Smithsonian Astrophysical Observatory.
Funct ...
on 28 May 1991 ().
Notes
References
External links
Asteroid Lightcurve Database (LCDB) query form
)
Dictionary of Minor Planet Names Google books
– Observatoire de Genève, Raoul Behrend
– Minor Planet Center
*
*
{{DEFAULTSORT:Saheki
004606
Discoveries by Tsutomu Seki
Named minor planets
19871027